FXLS896xAF AN12004 - 'No Motion' vs 'Freefall'

[andrewneil]

In the AN12004 Application Note, the basis for detecting  both 'No Motion' (3.2) and  'Freefall' (3.4) is that all 3 axes are within some threshold.

So that's the key to distinguishing 'No Motion' and  'Freefall' - as they're both detected on the same basis?

[TomasVaverka]

Hello Andrew,

The key to distinguishing between the two lies in the setting of the debounce time (2.55s vs. 100ms). And yes, we also recommend to use slightly different threshold values (±100mg vs. ±200mg).

BR, Tomas

[andrewneil]

So you're just assuming that a "brief" period of "no motion" must be "freefall" ?

The other difference is that the "no motion" example uses the Data[n]-Data[n-1] reference update mode, whereas "freefall" uses the Absolute mode.

What's the significance in that?

[andrewneil]

Still wondering about the significance of Data[n]-Data[n-1] vs Absolute reference?

Also, rather than using the 'AND' logic of all 3 axes, what would be the pros/cons of just using the VECM (vector magnitude) ?